A Layer 7 load balancer is more sophisticated and more powerful. It
inspects packets, has access to HTTP and HTTPS headers, and (armed
with more information) can do a more intelligent job of spreading the
load out to the target.
https://aws.amazon.com/blogs/aws/new-aws-application-load-balancer/
I understand the AWS Application Load Balancer has access to the HTTP(S) request headers but I can only see how you can route via the path. Can someone explain how I can route based on the user-agent header. If it's not possible, please suggest an alternative AWS method.
Till 2017-05-26 ALB doesn't have header based routing. With a update on 2017-04-05 it has included Host based routing. Currently it supports only path and host based routing. You can visit here for latest AWS information.
If you want to route based on headers ,currently there are no options in ALB.
You have to have an additional layer either like a proxy / nginx servers.
Flow can be something like this below.
Client calling https://example.com
ALB's DNS is configured to example.com
ALB has Target group attached to it which has nginx instances. Nginx instances routes to respective Load balancer with the header information. ( eg. if customerId is 123 route to ELB 1 else route to ELB 2 )
Two ELB has different EC2 instances attached to it.
But heard AWS is working on routing request based on the headers.
For anyone looking now, as of March 27 2019, ALBs now support routing based on HTTP headers other than the Host header.
Related
I have deployed 2 services in ECS Web and API, Both of the services have their ALB, How can I configure my domain as follows:
example.com -> Web ALB
example.com/api -> API ALB
I tried creating a single ALB for both web and api target group and added a path based routing in rules but /api request is received by nodejs with full path, Eg. if a call example.com/api/products node is getting /api/products instead of /products
What could be a proper way of implementing this?
Thanks!
call example.com/api/products node is getting /api/products instead of /products
That's correct and that's how it should work. In other words, ALB can't change path from /api/products to /products, because ALB only forwards requests, it does not re-write them.
You can have a look at CloudFront, which could be helpful in that case.
I have 3 containers deployed on ecs and traffic is distributed by an application load balancer, swagger on this individual containers can be accessed via e.g 52.XX.XXX.XXX/swagger.
I need the services to be accessed via for e.g:
52.XX.XXX.XXX/users/swagger
52.XX.XXX.XXX/posts/swagger
52.XX.XXX.XXX/comments/swagger
I've tried add the following the loadbalancer rules
PATH /users* or /users/
PATH /posts* or /posts/
PATH /comments* or /comments/
I get a 404 error when i visit the load balancer dns for example myapp-lb-4283349.us-east-2.elb.amazonaws.com/users/swagger
You can't achieve that with AWS Load Balancer alone. AWS LB doesn't re-route traffic based on paths. They just forwards the incoming traffic to origin.
Your service should be accessible via 52.XX.XXX.XXX/user/swagger 52.XX.XXX.XXX/posts/swagger etc. in order for Load Balancer to forward it. You can't forward (or re-route) your traffic from Load Balancer like this:
LB_URL/user/swagger -> IP/swagger
The missing /user/ part is not something Load Balancer can do for you. Update your application itself and add specific routes which you want to listen on.
Framework: .Net core 2.0
Hi everyone,
I have deployed let's say 3 applications on the same EC2 instance which are websites (front end angular js and 2 web apis for authentication and communication). How do I setup a single load balancer for catering requests for all of the 3 websites using HTTPS?
These websites communicate among each other for authentication and providing the required data between them.
The websites are deployed on the EC2 using hostnames on the IIS and they are accessible directly through the hostnames. Is there another/better way to deploy them instead of hostnames only?
When setting up a load balancer, you would have to configure listeners for it, wherein you mention the ports through which you would want to access your application. And in the listeners you would have to mention target groups to which you would route traffic, based on hostnames / host headers.
So, here are the steps to follow.
Since all your traffic has to anyway go to the same instance, you would have to create one target group and register the instance that you have already created with traffic routed through the 80 port.
Now, coming back to the ELB configuration, you would need to create a HTTP listener (port 80) that would have a default rule to redirect all traffic to HTTPS (port 443).
In the same ELB, create a HTTPS:443 listener, where (usually) you would have different listener rules depending on what are the hostnames of your sites in IIS. But just for simplicity, configure the default rule to route all traffic to the target group created in the step above (once we check if traffic is flowing right, we can change the configuration to improve security).
That's all!
With the right security group whitelisting, your traffic should flow into your instance through the ELB.
Congratulations! That should be enough...
... unless you want to make sure that ONLY the requests related to those sites flow into your instance, then, once you are sure that the traffic flow is right, you can create another listener rule in your ELB's HTTPS:443 listener, wherein you can configure the following setting:
IF Host Header is frontend.website.com OR webapi1.website.com OR webapi2.website.com THEN Forward to (target group created in Step 1)
Sorry in advance if this doesn't make much sense. I'm fairly new to this, so bear with me please.
I'm trying to specify a domain to a specific folder depending on the domain name the user use (example.com or test123.com), through Amazon Elastic Load Balancer (Application load balancer to be specific).
My current setup is that all traffic from the internet goes to a Load Balancer (ELB), from there it round robin between 2 EC2 instances. Both instances are connected to an Amazon Network File System (EFS), as well as a Relational Database (RDS).
I can access the website(s) fine through the DNS of the load balancer (http://web-load-balancer-efs-16512354.us-east-1.elb.amazonaws.com/example/)
What I want to do now set it up so that if someone put example.com as their url it will point to the Load Balancer and from there the server will use the correct folder as root (www.example.com document root would be http://web-load-balancer-efs-16512354.us-east-1.elb.amazonaws.com/example/, but the URL will still be www.example.com).
I created a hosted zone on Route 53 to point the domain name to my load balancer, but currently my load balancer which leads to one of the ec2 instances. Currently the ec2 document root is /var/www/html/efs-mount/.
Is there a way for me to have multiple document root depending on the domain name?
I stumble on something about putting multiple TLS/SSL certificate on your listener and through SNI protocol it'll be able to find right place? http://docs.aws.amazon.com/elasticloadbalancing/latest/application/create-https-listener.html#https-listener-certificates. I'm not sure if this is what I need, or I'm completely off track.
If someone can point me to the right direction on how to do this that would be great.
Thanks
You are indeed off track.
While ALB with multiple SSL certificates may be a part of your strategy, since it allows you to attach multiple ACM certificates to a single instance or group of instances, ALB does not re-write the paths of the incoming requests or determine how the instance resolves web paths into filesystem paths.
This is something configured in your web server itself. Start by searching for something like "name based virtual hosting." Each domain name will specify it's own "document root" in the web server configuration files.
We are implementing a micro-services architecture in AWS. We have several EC2 instances which has the micro-services deployed on different ports. We also have an internet facing Application Load Balancer, which routes to different services based on the port.
eg:
xxxx-xx.xx.elb.amazonaws.com:8080/ go to microservice 1
xxxx-xx.xx.elb.amazonaws.com:8090/ go to microservice 2
We need to have a domain name instead of the ELB, the port should not be exposed through the domain name as well. Almost all the resources I found regarding route 53, use alias which does the following:
xx.xxxx.co.id -> xxxx-xx.xx.elb.amazonaws.com or
xx.xxxx.co.id -> 111.111.111.11 (static ip)
1) Do we need separate domains for each micro service?
2) How to use alias to point domains to a specific port of the ELB?
3) Is it possible to use this setup if the domains are from another provider other than AWS.
Important Update
Since this answer was originally written, Application Load Balancer introduced the capability for ALB to route requests to a specific target group based on the Host header of the incoming request.
The incoming host header can now be used to route requests to specific instances and ports.
Additionally, ALB introduced SNI support, allowing you to associate multiple TLS (SSL) certificates with a single balancer, and the correct certificate will be automatically selected based on the SNI presented by the client when TLS is negotiated. Multi-domain and wildcard certs from Amazon Certificate Manager also work with ALB.
Based on these factors, no separate ports or different listeners are needed -- simply assign hostnames and/or path prefixes for each service, and map those patterns to the appropriate target group of instances.
The original answer is no longer accurate, but is included below.
1.) Do we need separate domains for each micro service?
No, this won't help you. ALB does not interpret the hostname attached to the incoming request.
Separate hostnames in the same domain won't directly accomplish your objective, either.
2.) How to use alias to point domains to a specific port of the ELB?
Domains do not point to ports. Hostnames do not point to ports. DNS is only used for address resolution. This is true everywhere on the Internet.
3.) Is it possible to use this setup if the domains are from another provider other than AWS.
This is not a limitation of AWS. DNS simply does not work this way.
A service endpoint is unaware of the DNS records that point to it. The DNS entry itself is strictly used for discovering an IP address that can be used to access the endpoint. After that, the endpoint does not actually know anything about the DNS, and there is no way to tell the browser, via DNS, to use a different port.
For HTTP, the implicit port is 80. For HTTPS, it is 443. Unless a port is provided in the URL, these are the only usable ports.
However, in HTTP and HTTPS, each request is accompanied by a Host: header, sent by the web browser with each request. This is the hostname in the address bar.
To differentiate between requests for different hostnames arriving at a device (such as ELB/ALB), the device at the endpoint must interpret the incoming host header and route the request to an back-end system providing that service.
ALB does not currently support this capability.
ALB does, however, support choosing endpoints based on a path prefix. So microservices.example.com/api/foo could route to one set of services, while microservices.example.com/api/bar could route to another.
But ALB does not directly support routing by host header.
In my infrastructure, we use a combination of ELB or ALB, but the instances behind the load balancer are not the applications. Instead, they are instances that run HAProxy load balancer software, and route the requests to the backend.
A brief example of the important configuration elements looks like this:
frontend main
use_backend svc1 if { hdr(Host) -i foo.example.com }
use_backend svc2 if { hdr(Host) -i bar.example.com }
backend svc1
server foo-a 192.168.2.24:8080
server foo-b 192.168.12.18:8080
backend svc2
....
The ELB terminates the SSL and selects a proxy at random and the proxy checks the Host: header and selects a backend (a group of 1 or more instances) to which the request will be routed. It is a thin layer between the ELB and the application, which handles the request routing by examining the host header or any other characteristic of the request.
This is one solution, but is a somewhat advanced configuration, depending on your expertise.
If you are looking for an out-of-the-box, serverless, AWS-centric solution, then the answer is actually found in CloudFront. Yes, it's a CDN, but it has several other applications, including as a reverse proxy.
For each service, choose a hostname from your domain to assign to that service, foo.api.example.com or bar.api.example.com.
For each service, create a CloudFront distribution.
Configure the Alternate Domain Name of each distribution to use that service's assigned hostname.
Set the Origin Domain Name to the ELB hostname.
Set the Origin HTTP Port to the service's specific port on the ALB, e.g. 8090.
Configure the default Cache Behavior to forward any headers you need. If you don't need the caching capability of CloudFront, choose Forward All Headers. Also enable forwarding of Query Strings and Cookies if needed.
In Route 53, create foo.api.example.com as an Alias to that specific CloudFront distribution's hostname, e.g. dxxxexample.cloudfront.net.
Your problem is solved.
You see what I did there?
For each hostname you configure, a dedicated CloudFront distribution receives the request on the standard ports (80/443) and -- based on which distribution the host header matches -- CloudFront routes the requests to the same ELB/ALB hostname but a custom port number.
I think there is a possibility that he can build what he's describing. I was in the same boat for a while, here's some options for you to consider:
In R53 create a hosted zone - and point your domain at it.
Optional step: create ALIAS records. You can do this for each subdomain or
app. Leave the ALIAS field blank if using the root domain.
Create a record set using the SLA option, which is a service lookup for port
redirection. Try to point this to your LB port 80, alias the sub-domains.
Change your load balancer's listeners, to listen on port 80 - then redirect app traffic based on your apps port settings.
I havent used SLA, but this would definitely point you in that direction.